The present invention generally relates to a safety belt or harness for restraining, such as that utilized in restraining aircraft passengers, automobile passengers and window washers, and more particularly, to a belt which indicates that it has been subjected to a predetermined high tensile force. In automobiles, the belts are used to restrain passenger movement during sudden deceleration of vehicles.
Safety belt and harness manufacturers generally utilize woven materials such as polyester, nylon, rayon and combinations of these fabrics. The present invention provides a means for noting to the belt user or to a repairman that the belt has experienced a tensile force above a predetermined tensile force. This warning system or indicator is desirable to indicate that the seat belt system has been subjected to extreme tensile stress, for example, when worn by a passenger during an automobile accident. This latter benefit provides a means of noting, or at least one indication of the fact, that the user may have been utilizing this belt in the prescribed manner to restrain him during an accident. Thus, the manufacturer is at least given some partial information that the belt was utilized at some point in time for restraining a wearer during a rapid deceleration, such as an accident. Also, the retractor mechanism itself may be damaged if an extremely high load had been applied during a previous accident. Hence, a warning that the seat belt system should be checked or replaced is desirable. As an attempt at providing a warning to a user, at least one manufacturer of a belt apparatus provides multicolored threads within the belt warp or weft. In this fabric each of the several colors are indicative of threads of varying tensile strength, which threads, when ruptured, expose frayed ends indicating the degree of stress and the fact that the belt no longer has all of its original stress and elongation characteristics.
Warning means provided by various belt suppliers are not considered adequate for present safety belt arrangements, especially in automotive vehicles. It has been suggested to fold over a portion of a seat belt and sew the folded over portion with thread, which will break at a predetermined load. Within the fold may be a warning label that the belt should be replaced, and when the stitches are broken, the fold is unfolded to expose the warning. This unfolding results in increased belt length at the time of an accident. The increased belt length is undesirable because it allows the wearer to move forward before being restrained. The sewing must be done at a location where there are sewing machines and, once done, the belt having the folded loop must be of a particular length. It is more desirable to be able to provide long rolls or lengths of belt and then cut them to the desired length for a particular vehicle with a retractor and belt assembly. Further, the added cost of a sewing operation and the folded belt length, which is not used until the stitches are broken, increases the cost of this system.
The present warning system provides an improved and less costly means for noting a highly stressed condition of the belt, which is less likely to be questioned should the issue of belt extension and operability arise either from liability or when a belt is noted for replacement during repair work.